Field of the Invention and Related Art Statement
The present invention relates to an optical instrument for reproducing an original in normal daylight conditions and particularly to a camera operable in a light room, for forming an original image on photosensitive material or tracing paper with a desired magnification.
FIG. 1 is a perspective view of a conventional camera of the above mentioned type. FIG. 2 is a side view of the camera shown in FIG. 1. The camera illustrated in FIGS. 1 and 2 is capable of reproducing an original in normal daylight conditions. The camera includes: a base frame 22 which is supported stably on a floor by means of casters 20 and a main frame 24 for forming a copy image therein The main frame 24 is fixed on one end portion of the base frame 22. The camera further includes an original holder 26 which is provided on the other end portion of the base frame 22 and which is slidable toward the main frame 24. The original holder 26 holds an original to be copied such that the original is directed toward the main frame 24. A light source 28 for illuminating the original is provided on the original holder 26. A film processor 30 is provided on the main frame 24. The film processor 30 processes photosensitive film exposed in the main frame 24. A platen cover 32 covers the upper surface of the main frame and the film processor 30 to define a dark space inside. A lens holder 34 is provided on the base frame 22 between the main frame 24 and the original holder 26. The lens holder 34 is slidable between the main frame 24 and the original holder 26. The lens holder 34 holds a lens which is adapted to form a reproduced image of the original in the main frame 24. A bellows 36 connects the lens holder 34 and the main frame 24 to shield an optical path of rays passing through the lens from the environment.
The main frame 24 includes a mirror 38 provided on an optical axis from the original holder 26 and through the lens holder 34. The mirror 38 has a prescribed inclination (e.g., 45.degree.) with respect to the optical axis. The mirror 38 reflects a beam from the original upward The main frame 24 further includes an image formation platen 40 provided on the upper surface of the main frame 24. An image of an original is formed on the upper surface of the frame 24 by the beam reflected by the mirror 38 An operation panel 42 is provided on the upper surface of the main frame 24. The operator uses the panel 42 to set the reproduction ratio or the like.
The side on which the operation panel 42 is provided is hereinafter referred to as the front side. The side on which the original holder 26 is mounted is hereinafter referred to as the back side. A frame 46 is provided on the back side of the main frame 24 and the film processor 30 is fixed on the frame 46. A photosensitive material storing box 44 for storing photosensitive material (such as photosensitive film) is provided under the film processor 30.
The cover 32 is openable and closable so that the platen 40, the storing box 44 and the film processor 30 can be shut off from external light to form a dark space. The cover 32 has a pair of operation holes 48 on its front surface into which the operator inserts his arms to handle the photosensitive film inside the cover 32. The photosensitive film is discharged from an outlet opening 50 after the film is processed by the processor 30. The operator can look though a window 52. The window 52 includes, for example, a red transparent place which covers an opening 53 formed in the platen cover 32. The window 52 intercepts rays which would cause damage to the photosensitive material.
The cover 32 can be opened to form a right angle with the upper surface of the main frame 24. The holder 26 can be rotated to a horizontal position (FIG. 2) to make it easy to place an original thereon.
FIG. 3 is a side sectional view of the film processor 30. The processor 30 includes: a drive motor 54 which is fixed on the frame 46; a developing bath 56, a fixing bath 58 and a rinsing bath 60; a drier 62; and a rotation transmission shaft 70 connected through a sprocket 66 and a chain 68 to a drive shaft 64 of the drive motor 54. The shaft 70 is supported on the lateral surfaces of the baths 56 to 60. Driven shafts 72 are supported by concave portions formed on the sides of the respective baths 56 and 60. The shafts 72 can be removed from the shaft 70. Roller rack units 74 are detachably set in each of the baths 56 to 60. A tray 80, on which a processed film is placed, is provided in the outlet opening 50 of the platen cover 32.
FIG. 4 is an enlarged cross-sectional view of the lens holder 34 shown in FIG. 2. The lens holder 34 includes a lens support 82 which is movably mounted on the base frame 22; a cylindrical lens hood 84 which is attached to the lens support 82 on the side of the main frame 24; and a long focal point type lens 86 at the center of the top end of the lens hood 84. The lens 86 faces the main frame 24 and its optical axis is directed toward the original holder 26.
In operation, to obtain a reproduction of an original with a desired magnification, an original is fixed on the original holder 26. The original is illuminated by the light source 28. Part of the light reflected from the original enters the lens hood 84 through its opening. The light passes through the lens 86 and is reflected by the mirror 38. The light reaches the platen 40.
The lens holder 34 and the original holder 26 slide on the base frame 22. When the operator sets a reproduction ratio (using the operation panel 42) the lens holder 34 and the original holder 26 move in back-and-forth directions by means of a drive unit (not shown) so that the image of the original is formed on the platen 40 with the desired magnification.
If the operator places (beforehand) a photosensitive material, such as a film, on the platen 40 for exposure, a latent image of the original is formed thereon. After exposure, the operator inserts his arms into the platen cover 32 through the operation holes 48. The operator feeds the film to the processor 30, while observing the inside of the platen cover 32 through the window 52.
The film 78 moves along the film transport path 76 within each roller rack unit 74 by the rotation of the drive motor 54 (as well as by the rotation of the transmission shaft 70 and the related driven shaft 72). The film 78 moves through the developing bath 56, the fixing bath 58, and the rinsing bath 60. The film 78 is dried by the drier 62 after it comes out of the rinsing bath 60. The processed film 78 is discharged through the outlet opening 50 and stacked on the tray 80.
If the platen cover 32 is opened (FIG. 2) and a sheet of tracing paper is placed on the platen 40 (instead of the film), the image formed on the platen 40 can be traced. This function is utilized for various cases such as layouts of designs or captions in the design industry or formation of block copies in the plate making industry.
However, the conventional apparatus has several disadvantages. First, it is difficult to reduce the size of the conventional camera without degrading the camera's performance. The mirror 38 reduces the size of the entire apparatus by changing the optical path. However, when the camera has such a mirror 38, light from outside of the effective photographing range, but passing through the focusing lens, might be incident directly on the photographing surface or the inside of the camera. This is referred to herein as flare light. Flare light adversely affects the quality of the photographed image
FIG. 5 illustrates the principle of flare generation. Referring to FIG. 5, a circle 88 represents an effective photographing range on the original holder 26. A circle 90 represents an image forming range on the platen 40. Light from the holder 26 reaches the lens 86 through the path shown by dot-dash lines. Light passing through the lens 86 is turned by the mirror 38 and converged on the platen 40.
Part of the light passing through the path shown by the hatched areas reaches the platen 40 directly, i.e., without passing through the mirror 38. These rays are not appropriately converged to form an image on the platen 40. This is flare light. The flare light adversely affects the quality of the image formed by the other light. The hatched area 92 in the circle 90 represents the range of the flare light's adverse effect.
To avoid direct incidence of flare light on the platen 40, a method of setting the effective photographing area for example to a reduced range and decreasing the size of the platen 40, or a method of increasing the distance D between the mirror 38 and the platen 40 may be considered. However, the former method fails to meet the art's need to enlarge the effective photographing area. With the latter method, it is necessary to decrease the distance between the lens 86 and the mirror 38 to obtain a prescribed magnification. The mirror 38 restricts the range of travel of the lens 86. As a result, sometimes the lens 86 cannot move to the position necessary to achieve a desired reduction because the mirror 38 obstructs the lens 86. As a result, reduction cannot be satisfactorily obtained.
Another disadvantage of the conventional camera is that it is difficult to trace an image of an original in normal daylight conditions. In the conventional apparatus, the platen cover 32 is fully opened (for example at 90.degree.) to facilitate exchange of film cases or maintenance of the film processor 30. A large amount of light is applied from the environment to the platen 40. The light applied from the environment to the platen 40 becomes brighter than the image formed on the platen 40 by the illumination of the light source 28 As a result, the image of the original formed on the platen 40 becomes very difficult to see. This makes it difficult to trace the image of the original.
Further, the conventional camera is difficult to maintain. Generally, periodic maintenance is required for the film processor 30 to maintain high quality. The roller rack units 74 can be taken out from the baths 56, 58 and 60 to facilitate maintenance, i.e., to rinse the roller rack units 74 and the respective baths 56, 58 and 60.
But when the baths 56, 58 and 60 are to be rinsed, the electric parts and the like might be splashed with the dispersed rinsing water. Rinsing the baths 56, 58 and 60 is also troublesome.
In addition, it is not easy to clean the roller rack units 74. Particularly, in order to clean the photosensitive film transport path 74 formed in each roller rack unit 74, it is necessary to remove a guide member of the film transport path 76 from the roller rack unit 74 (by using a driver or the like).